37 GHz methanol masers : Horsemen of the Apocalypse for the class II methanol maser phase?

We report the results of a search for class II methanol masers at 37.7, 38.3 and 38.5 GHz towards a sample of 70 high-mass star formation regions. We primarily searched towards regions known to show emission either from the 107 GHz class II methanol maser transition, or from the 6.035 GHz excited OH transition. We detected maser emission from 13 sources in the 37.7 GHz transition, eight of these being new detections. We detected maser emission from three sources in the 38 GHz transitions, one of which is a new detection. We find that 37.7 GHz methanol masers are only associated with the most luminous 6.7 and 12.2 GHz methanol maser sources, which in turn are hypothesised to be the oldest class II methanol sources. We suggest that the 37.7 GHz methanol masers are associated with a brief evolutionary phase (of 1000-4000 years) prior to the cessation of class II methanol maser activity in the associated high-mass star formation region.Comment: 14 pages, 4 figures, accepted for publication in Ap

Causal sites as quantum geometry

We propose a structure called a causal site to use as a setting for quantum geometry, replacing the underlying point set. The structure has an interesting categorical form, and a natural "tangent 2-bundle," analogous to the tangent bundle of a smooth manifold. Examples with reasonable finiteness conditions have an intrinsic geometry, which can approximate classical solutions to general relativity. We propose an approach to quantization of causal sites as well.Comment: 21 pages, 3 eps figures; v2: added references; to appear in JM

12.2-GHz methanol maser MMB follow-up catalogue - II. Longitude range 186 to 330 degrees

We present the second portion of a catalogue of 12.2-GHz methanol masers detected towards 6.7-GHz methanol masers observed in the unbiased Methanol Multibeam (MMB) Survey. Using the Parkes radio telescope we have targeted all 207 6.7-GHz methanol masers in the longitude range 186 to 330 degrees for 12.2-GHz counterparts. We report the detection of 83 12.2-GHz methanol masers, and one additional source which we suspect is thermal emission, equating to a detection rate of 40 per cent. Of the 83 maser detections, 39 are reported here for the first time. We discuss source properties, including variability and highlight a number of unusual sources. We present a list of 45 candidates that are likely to harbor methanol masers in the 107.0-GHz transition.Comment: Accepted MNRAS 19 July 201

Higher-dimensional Algebra and Topological Quantum Field Theory

The study of topological quantum field theories increasingly relies upon concepts from higher-dimensional algebra such as n-categories and n-vector spaces. We review progress towards a definition of n-category suited for this purpose, and outline a program in which n-dimensional TQFTs are to be described as n-category representations. First we describe a "suspension" operation on n-categories, and hypothesize that the k-fold suspension of a weak n-category stabilizes for k >= n+2. We give evidence for this hypothesis and describe its relation to stable homotopy theory. We then propose a description of n-dimensional unitary extended TQFTs as weak n-functors from the "free stable weak n-category with duals on one object" to the n-category of "n-Hilbert spaces". We conclude by describing n-categorical generalizations of deformation quantization and the quantum double construction.Comment: 36 pages, LaTeX; this version includes all 36 figure

Establishing a baseline for the study of maritime cultural heritage in the Gaza Strip

As a result of its geographic location, cultural diversity and historical trajectory, the Gaza strip is a key zone of scholarly enquiry and has a central role in the historical, social, political, economic, legislative and environmental discourses for the wider region. Existing historical knowledge of Gaza is dominated by combative narrative trends that emphasise the events of the 20th and 21st centuries and invoke archaeology extensively. In this context, cycles of material preservation and damage—often accompanying other forms of violence—have attracted the attention of academics and international media. Among the corollaries of this situation, is the destruction and marginalisation of vulnerable cultural heritage, particularly maritime cultural heritage, which is subjected to additional environmental, climatic, and anthropogenic pressures. As a means of countering the challenges on current field research in the region and to further assess the damage and threats faced by archaeological fabric, this paper combines data from coastal and archaeological research conducted in the Gaza Strip to create a benchmark for the study of its maritime archaeology. Additional information on the alteration of coastal landscape is deduced through the analysis of aerial photographs and satellite imagery. This study falls within the scope of the Maritime Endangered Archaeology in the Middle East and Africa Project (MarEA). MarEA aims to comprehensively document and assess vulnerable maritime archaeology (underwater, nearshore, coastal) and produce baseline information that can enhance existing infrastructure on archaeological monitoring and management.</p